CDC/RDC Interview Q&A Bank: Silicon PPA Impact

Silicon PPA and reliability impact

Real-world scenarios test containment and escalation instincts.

Area drivers

• extra synchronizer stages

• FIFO buffering

• diagnostic observability logic

Power drivers

• additional flops

• always-on reset logic

• debug monitors

Timing/latency impact

• added latency through synchronizers

• pointer synchronization delays

PD consequences

• placement proximity of sync stages

• clock/reset tree interactions

Verification burden

• formal liveness reruns

• stress simulation matrix

PPA / RELIABILITY — CDC/RDC Interview Q&A Bank
area/power/latency vs reliability margin

Key takeaways

• Reliability has implementation cost

• Track that cost explicitly in signoff decisions

Design option reliability curve

METASTABILITY ENVELOPE — CDC/RDC Interview Q&A Bank

probability of unresolved state
  ^
  |\
  | \
  |  \
  |   \
  +------------------------------> settle time
      short settle      long settle

Design lever: more settle time and correct synchronizer topology increase MTBF.

CDC/RDC deep dive

Interview performance reflects production signoff thinking quality.

Concept diagram

INTERVIEW FLOW

classify -> explain mechanism -> propose fix -> state regression

Metric graph

PRACTICE SCORE

session1 62%
session2 78%
session3 89%

Reports and artifacts

• scenario completion

• answer rubric scores

• trap recovery quality

Mini case study

Candidate gave command-heavy answer but missed risk framing and waiver governance.

Debug branches

• Use mechanism-first structure

• name ownership and evidence

• close with signoff decision

Senior review question

Ask: what evidence proves this risk is closed for silicon, not just tool-clean?

Key takeaways

• State crossing class, assumptions, and owner with every issue.

• Run structural and dynamic regressions after each fix.

Common pitfalls

• Treating all warnings as equivalent risk.

• Waiving issues without containment evidence.

• Skipping reset and reconvergence stress after CDC fixes.